1. Field of the Invention
The present invention relates to a vehicle control apparatus for permitting use of a vehicle.
2. Description of Related Art
A vehicular electronic key system for permitting use of a vehicle is known in the art (see, for example, JP-A-2004-114860). JP-A-2004-114860 discloses a vehicular electronic key system including a control apparatus mounted to a vehicle and an electronic key (portable machine) for transmitting a response signal based on reception of a request signal from the control apparatus. The control apparatus is provided with request signal generating means for outputting the request signal at previously set constant time periods (10-100 seconds) to the electronic key when an engine is operated.
In JP-A-2004-114860, since the period of outputting the request signal to the electronic key is previously set to a constant time period (10-100 seconds), when the period of outputting the request signal is set to a relatively long period, for example to 100 seconds, there is a problem at high running speeds in that, when an alarm is output, the vehicle may have already moved a long distance from the location where the electronic key was dropped. On the other hand, when the period of outputting the request signal is set to a relatively short period, for example to 10 seconds, there is a problem in that when the vehicle is stopped, even though the user already knows that the electronic key is dropped, consumption of a battery of the electronic key is increased since the output of the request signal continues to be carried out at a comparatively short interval of 10 seconds.